The present invention relates to a semiconductor laser device, and, more particularly, to a high-output semiconductor laser used as a light source for laser beam printers, optical disks and laser machining equipment, as well as the method of manufacture thereof.
A conventional high-output semiconductor laser, as shown in a perspective view of FIG. 5, consists of a substrate 26, a block layer 27, a cladding layer 28, an active layer 29, a cladding layer 30 and a cap layer 31, stacked together in that order. The light-emitting end surface is covered with an insulating film 13 such as Al.sub.2 O.sub.3 to prevent chemical reaction to thereby protect the end surface against chemical damage. Such high-output semiconductor lasers are described in an article entitled "Water Vapor, Facet Erosion, and the Degradation of (Al,Ga)As DH Lasers Operated at CW Output Powers of Up to 3 mW/.mu. Stripewidth" by John A. F. Peek in the "IEEE Journal of Quantum Electronics" QE-1 7(5), pages 781-787, 1981.
The above-mentioned conventional high-output semiconductor laser has planar end surfaces comprised of at least the cladding layers 28, 30 and the active layer 29 on the light-emitting side. These three layers are stacked together and cleaved with the cleaved surface having the insulating film 13 formed directly over it. Hence, although it is possible to protect the semiconductor laser emitting end surface from chemical corrosion, first levels of recombination of a surface state that occur at the boundary between the semiconductor and the insulating film cannot be prevented completely, so that heat produced by recombination at the surface state may result in optical damage at the end surface. The higher the output of the semiconductor laser, the more likely the optical damage at the end surface will be.